Indeed it is. And I for one am darn thankful for it!
If he is talking about the KERNEL, he has a bit of a point, if one generously interprets his remarks in a narrow way: SUN, Solaris, MIPS, AIX, etc (all more or less blueblood UNIX whose geneology goes back to Bell Labs v6 or before) have all seen their day and are slipping away into the SUNset (PUN of course).
However, OpenBSD and OS X are quite alive and will carry on the tradition.
I am CERTAIN that Linux has incorporated some of the code/features of OpenBSD and the OpenSource portions of the original UNIX kernel, just because Linux incorporates whatever works and is convenient, and does not try to maintain some kind of absurd "racial purity", so what Dell is saying is B**S*** in any event, and meaningless to boot.
It is Linux, and not M$ that is the BORG and even M$'s best will be absorbed by Linux (whether or not M$ best is worth keeping is subject to INTENSE debate -- VIRUSES and remote administration TROJANS anyone?)
LOL.
"I liken starting one's computing career with Unix, say as an undergraduate, to being born in East Africa. It is intolerably hot, your body is covered with lice and flies, you are malnourished and you suffer from numerous curable diseases. But, as far as young East Africans can tell, this is simply the natural condition and they live within it. By the time they find out differently, it is too late. They already think that the writing of shell scripts is a natural act."
Ken Pier, Xerox PARC